class Subclass-name extends Superclass-name {
    //methods and fields
}

class Employee {
    float salary = 40000 ;
}

class Programmer extends Employee {
    int bonus = 10000 ;
    public static void main(String args[]){
        Programmer p = new Programmer();
        System.out.println("Programmer salary is : " + p.salary);
        System.out.println("Bonus of Programmer is : " + p.bonus);
    }
}

class A{
    void msg(){
        System.out.println("hello");
    }
}
class B{
    void msg(){
        System.out.println("welcome");
    }
}
class C extends A,B { //suppose if it were
    public static void main(String args[]){
        C obj = new C();
        obj.msg(); //Now wich msg() method be invoked?
    }
}

class Animal{
}

class Dog extends Animal {
    public static void main(String args[]){
        Animal a = new dog();
        Dog b = (Dog) a;
    }
}

public class GeometricObject1 {
    private String color = "white";
    private boolean filled;
    private java.util.Date dateCreated;
    /** Construct a default geometric object */
    public GeometricObject1() {
        dateCreated = new java.util.Date();
    }
    /** Construct a geometric object with the specified color
    * and filled value */
    public GeometricObject1(String Color, boolean filled) {
        dateCreated = new java.util.Date();
        this.color = color;
        this.filled = filled;
    }
    /** Return color */
    public String getColor() {
        return color;   
    }
    /** Set a new color */
    public void setColor(String color) {
        this.color = color;
    }
    /** Return filled. Since filled is boolean,
    its get method is named isFilled */
    public boolean isFilled() {
            return filled;
    }
    /** Set a new filled */
    public void setFilled(boolean filled) {
        this.filled = filled;
    }
    /** Get dateCreated */
    public java.util.Date getDateCreated() {
        return dateCreated;
    }
    /** Return a string representation of this object */
    public String toString() {
        return "created on " + dateCreated + "\ncolor: " +
        color + " and filled: " + filled;
    }
}

public class Circle4 extends GeometricObject1 {
    private double radius;
    public Circle4() {
    }
    public Circle4(double radius) {
        super();
        this.radius = radius;
    }
    public Circle4(double radius, String color, boolean filled) {
        super(color, filled);
        this.radius = radius;
        //setColor(color);
        //setFilled(filled);
    }
    /** Return radius */
    public double getRadius() {
        return radius;
    }
    /** Set a new radius */
    public void setRadius(double radius) {
        this.radius = radius;
    }
/** Return area */
    public double getArea() {
        return radius * radius * Math.PI;
    }
    /** Return diameter */
    public double getDiameter() {
        return 2 * radius;
    }
    /** Return perimeter */
    public double getPerimeter() {
        return 2 * radius * Math.PI;
    }
    /* Print the circle info */
    public void printCircle() {
        System.out.println(toString() + "The circle is
        created " + getDateCreated() +
        " and the radius is " + radius);
    }
    public String toString() {
        return "Circle WWWW " + getColor() +
        super.toString();
    }
}

public class Rectangle1 extends GeometricObject1 {
    private double width;
    private double height;
    public Rectangle1() {
    }
    public Rectangle1(double width, double height) {
        this.width = width;
        this.height = height;
    }
    public Rectangle1(double width, double height, String color, boolean filled) {
        this.width = width;
        this.height = height;
        setColor(color);
        setFilled(filled);
    }
    /** Return width */
    public double getWidth() {
        return width;
    }
/** Set a new width */
    public void setWidth(double width) {
        this.width = width;
    }
    /** Return height */
    public double getHeight() {
        return height;
    }
    /** Set a new height */
    public void setHeight(double height) {
        this.height = height;
    }
    /** Return area */
    public double getArea() {
        return width * height;
    }
    /** Return perimeter */
    public double getPerimeter() {
        return 2 * (width + height);
    }
}

public class TestCircleRectangle {
    public static void main(String[] args) {
        Circle4 circle = new Circle4(1);
        System.out.println("A circle " + circle.toString());
        System.out.println("The radius is " + circle.getRadius());
        System.out.println("The area is " + circle.getArea());
        System.out.println("The diameter is " + circle.getDiameter());
        Rectangle1 rectangle = new Rectangle1(2, 4);
        System.out.println("\nA rectangle " + rectangle.toString());
        System.out.println("The area is " + rectangle.getArea());
        System.out.println("The perimeter is " + rectangle.getPerimeter());
    }
}

class Vehicle{
    int speed = 50;
}

class Bike3 extends Vehicle{
    int speed = 100;
}

void display(){
    System.out.println(speed); // will print speed of Bike
}
public static void main(String args[]){
    Bike3 b = new Bike3();
    b.display();
}

class Vehicle{
    Vehicle(){
        System.out.println("Vehicle is created!");
    }
}

class Bike5 extends Vehicle{
    Bike5(){
        super(); //will invoke parent class constructor
        System.out.println("Bike is created");
    }
}
public static void main(String args[]){
    Bike5 b = new Bike5();
}

class Person{
    void message(){
        System.out.println("Welcome");
    }
}

class Student16 extends Person{
    void message(){
        System.out.println("Welcome to java");
    }
}

void display(){
    message() //will invoke current class message() method
    super.message() //will invoke parent class message() method
}

public static void main(String args{}){
    Student16 s = new Student16();
    s.display();
}

public class Faculty extends Employee {
    public static void main(String[] args) {
        new Faculty();
    }
    public Faculty() {
        System.out.println("(4) Faculty's no-arg constructor is invoked");
    }
}

class Employee extends Person {
    public Employee() {
        this("(2) Invoke Employee’s overloaded constructor");
        System.out.println("(3) Employee's no-arg constructor is invoked");
    }
    public Employee(String s) {
        System.out.println(s);
    }
}

class Person {
    public Person() {
        System.out.println("(1) Person's no-arg constructor is invoked");
    }
}

public class Apple extends Fruit {
}
class Fruit {
    public Fruit(String name) {
        System.out.println("Fruit's constructor is invoked");
    }
}

برنامه‌سازی پیشرفته

وراثت

فهرست مطالب

انتزاع (Abstraction)

کپسوله بندی (encapsulation)

تفاوت کپسوله بندی و انتزاع

چند ریختی (Polymorphism)

ارثبری (inheritance)

انواع ارث بری

ارث بری چندگانه

مثالی از ارث بری چندگانه :

Up/Down Casting

تمرین زیرکلاس و ابرکلاس

ارث بری از ابرکلاسها

کلمه کلیدی super برای فراخوانی متد کلاس والد

زنجیره سازنده ها

ردگیری اجرای کد

نکات اضافی

خودمون رو بسنجیم

پایان